We are towing a 2017 Jay Flight 27bhs with a 2014 Sierra double cab 1500 right now. I know the debate on what a half ton can do. But this is a personal thing for me. I do not feel comfortable at all pulling that trailer with this truck. Loaded it's just over 7000# so it's not a monster. But it's still a lot more than I feel comfortable with especially when my family is in there with me. I'd rather trade up on the truck than risk something bad happening because my truck "can" technically pull it.

So I've decided on a ford and I want a diesel because I love the torque and hp that it provides. But I'm hung up on a 350 for some reason. I think because I really want as much truck as I can get since I've been white knuckling with the 1500. I know that a 250 diesel will handle this thing just fine and they have the same engine and tranny. The major diff is really only the suspension and I can find used 250's for significantly less than 350's in my area. But for some reason I am hung up on the 350 I guess because I don't want to feel like the 250 is a mistake and have to buy my third truck in a year.

I'm looking at 2012 or newer so it willl be the 6.7 engine.

Am I crazy for being so hung up on the 350 or do I just need to chill out and go buy a 250 and be done with it?

I had a 1995 f 350 dually and it was very stable pulling my 338 rets but when I went to a newer 2011 I decided on the f 250 diesel and it also feels very stable pulling the same 338 rets ... The f350 will have a little higher rear end ratio which in my opinion is better designed for pulling and on mine when running 65 mph in 6th it is fine but a little below the rpms needed to feel peppy. at 70 it feels better but I don't like pulling at 70 and if I drop 6th gear and use 5th my rpms go to around 2000 and fuel economy suffers a little as a result. hope this helps but I do love the power of the 2011 and it is so much quieter than my old 7.3

We had this same decision to make in 2013. We ended up getting the 350. The facts were that for the approx $1000 more we got heavier suspension, heavier brakes, heavier driveline etc., along with larger payload. We could go with a larger fifth wheel in the future, if wanted.
Originally we thought we wanted a 250, gas model, but seeing these details side by side (like twice the torque), we grabbed a diesel model. What worked well for us was that the new 2014 models were out and just a few of the 2013s on the lot. They were drooling to deal.
You'll love whichever you decide on.

Am I crazy for being so hung up on the 350 or do I just need to chill out and go buy a 250 and be done with it?

I think crazy may be a prerequisite.
I was told there is very little differences between the 250/350, extra leaf in the rear spring pack and taller blocks 2" vs 3" or something similar and all the running gear was the same.
The "too much truck" argument is valid (we went from 4400# to 12700#) but I bought the 350 knowing we'd be heavy.
It's an excellent TV and the 6.7 is an OX (it loves to pull).
Now, let's start the 2WD vs 4WD "discussion".